<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
        "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
    <title>Title</title>
</head>
<body>
<script>
  setInterval(function () {
    var arr=["0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f"];
    var allcolor="";
    for(var i=0;i<6;i++){
      var num = parseInt(Math.random()*16);
      allcolor+=arr[num];
    }
    document.body.style.backgroundColor="#"+allcolor;
  },1000)
</script>
</body>
</html>
